Theoretical photoionization spectra for Mg-isoelectronic Cl5+ and Ar6+ ions

Autoionizing resonant structures of Mg-isoelectronic Cl5+ and Ar6+ ions for the removal of a 3s or 3p electron from initial and states have been studied using the eigenchannel R-matrix approach connected with multichannel quantum-defect theory (MQDT) at the R-matrix boundary. The resonant states are verified and analyzed using eigenphase gradients to get resonance locations Er, effective quantum numbers n*, and widths . It is noted that there are no former theoretical and experimental studies for photoionization cross sections of Mg-isoelectronic Cl5+ to compare with ours. For the Mg-isoelectronic Ar6+ ion, our calculated ionization thresholds are in good agreement with NIST data and Opacity Project (OP) results. The current photoionization cross sections for the Mg-isoelectronic Ar6+ ion are in general agreement with the OP results, except for resonance energy shifts and structures of a few resonances.